Chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and/or blends containing these compounds have conventionally been used as refrigerants, solvents, foam blowing agents, propellants and the like. However, because of their high chemical stability and long atmospheric lifetimes, such compounds, when released to the atmosphere, migrate to the stratosphere where they undergo photolysis and deplete the earth's protective ozone layer. CFCs particularly contribute to depletion of the ozone layer, with the HCFCs depleting the ozone layer to a lesser extent. As a result, production of CFCs and HCFCs has been and continues to be severely limited and is scheduled for phase out in many industrialized and non-industrialized countries.
Accordingly, a need exists to develop materials which can be used as efficient and economical substitutes for CFC and/or HCFCs in a wide variety of applications, including refrigeration, solvent use (for example in chemical manufacturing and solvent cleaning applications), polymer foam blowing, and propulsion (for example, aerosol propellants), and the like. The Nimitz et al U.S. Pat. Nos. 5,444,102, 5,562,861, 5,605,647 and 5,611,210 broadly disclose blends of fluoroiodocarbon compounds and various additives as substitutes for CFCs, HCFCs and/or Halons. The fluoroiodocarbon blends of Nimitz et al are disclosed as advantageous for use in a variety of applications, including refrigeration, solvent cleaning, foam blowing, aerosol propulsion and firefighting, owing to the desirable combinations of properties provided by such blends. For example, the blends are disclosed as nonflammable, non-toxic and environmentally benign in having zero ozone depletion potentials, low global warming potentials and negligible atmospheric and terrestrial environmental impacts.
While the compositions broadly disclosed by Nimitz et al are useful in a variety of applications, a need still exists for developing compositions with a particular combination of properties for more specific applications. For example, in the refrigeration area, suitable replacements for CFCs, HCFCs and/or HFCs must be non-flammable and unreactive and substantially non-fractioning over a wide range of temperatures, for example from about -98.degree. C. to about 90.degree. C., or even wider. While the majority of residential, commercial and institutional refrigeration devices operate in the range of from about -23.degree. C. to about 8.degree. C., and in extraordinary cases, higher temperatures may be experienced. Thus, suitable compositions for refrigeration must not significantly fractionate or change composition over these temperature ranges to avoid becoming flammable. Additionally, for compositions to be suitable refrigerant replacements for CFCs, HCFCs and/or HFCs, the compositions must exhibit good miscibility with refrigeration lubricants such as polyol ester lubricants. Further, in order for a composition to adequately serve as a replacement for CFCs, HCFCs and/or HFCs, the substitute compositions must be effective under the operating conditions of conventional refrigeration equipment, thereby serving as "drop in" replacements for CFCs, HCFCs and/or HFCs or "near drop in" replacements for such materials, requiring only minor changes in lubricant, equipment, for example expansion valves, or the like. In view of this combination of necessary properties, a need still exists for further development of suitable replacement materials, particularly for refrigeration applications.